[Car Tips] How to deal with heavy rain or flooding when driving
🌧 Let me tell you: The heavy rain in Hong Kong is no joke
In summer and early autumn, Hong Kong is often hit by heavy rainstorms due to the influence of monsoons, low-pressure troughs, and tropical cyclones. The Observatory has issued yellow, red, and black rainstorm warnings . Sometimes, the water can reach half the height of a car within a few minutes, especially in:
- Low-lying urban areas (such as Sham Shui Po, parts of Tseung Kwan O, and Kwun Tong)
- Tunnel entrances and exits (part of the Red Tunnel and Lion Tunnel)
- Water levels at flyovers (e.g. sections of Kwun Tong Bypass)
- Low-lying rural areas in the New Territories (Yuen Long, Kam Tin, Sheung Shui)
1️⃣ Why are heavy rain and flooding so dangerous for driving?
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Vision is greatly obstructed <br>Heavy rain will cause dense water droplets on the windshield, and the vision may be blurred even with the wipers turned on at full blast.
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Road friction drops sharply <br>The water layer reduces the contact between the tire tread and the ground, making it easy to aquaplaning.
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Reduced braking performance <br>When water enters the brake system for a long time, the brake response becomes slower.
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Risk of mechanical damage <br>Excessively high water level can enter the engine through the air intake, causing a fire (water in the cylinder).
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Hidden obstacles <br>Potholes, manhole covers, gravel, and debris on the road can be covered by water, making them extremely dangerous.
2️⃣ Common mistakes Hong Kong drivers make during heavy rain and flooding
- Forcing a flooded area : "Should have passed the test" → Engine stalls due to water ingestion
- Braking suddenly and twisting the steering wheel : encountering water at high speed, resulting in a tailspin and hitting an obstacle
- Following too closely to large vehicles : Vision is blocked, and you fall into the pit without seeing the disaster ahead.
- Ignoring the risks near rivers or drainage channels : Rainfall leads to rapid water rise and people are trapped
3️⃣ Driving in Heavy Rain (Urban Area)
🚦 Low speed, stable, and reserved distance
- Reduce the speed limit by 30%–50% compared to normal speed limits
- The distance to the vehicle in front is at least twice as long (due to the longer braking distance)
🚙 Turn on low beam or fog lights
- Make oncoming and following vehicles see you clearly
- Don't use high beams, as reflections can affect your vision.
🛑 Avoid low-lying waterlogging
- Pay attention to the reflections on the ground and the different colors, there may be deep water locations
⏱ Delayed travel/reroute
- If you receive a black rain or flooding warning, try to wait until the rain subsides before setting off.
- Check road sections using real-time information from the Transport Department, Police Force and Hong Kong Observatory
4️⃣ Driving in flooded areas (if unavoidable)
① Determine water depth
- Use roadside signs, curbs or pedestrian ankles to visually inspect
- If the height exceeds half the wheel height (20-30cm), it is not recommended to force your way in.
②Low-speed steady driving
- Use first or second gear (manual transmission), L gear (automatic transmission)
- Maintain a steady speed of about 5–10 km/h and avoid sudden acceleration or reduction.
③Keep the engine at high speed
- Adding a small amount of fuel will increase the engine speed and reduce the chance of water entering the exhaust pipe.
④Avoid side waves
- If a large vehicle passes by and creates waves, you should slow down or stop and wait for the waves to pass.
⑤ Once the engine dies, do not try to restart it.
- Because it may cause serious damage to the engine (restarting after entering water, bent crankshaft, broken piston)
- You should immediately turn on the hazard lights, lock the car, call the insurance company or ask for a tow truck.
5️⃣ Special attention: Motorcycles and bicycles
Many food delivery drivers and delivery drivers in Hong Kong will work even during heavy rain, but two-wheeled vehicles are even more dangerous:
- If the water covers the manhole, the front reel may fall and the balance may be immediately lost.
- Water waves can directly hit people's knees and affect their center of gravity.
- Try to avoid sections of road where the water depth exceeds half a wheel and stop in a safe place to take shelter from the rain
6️⃣ Real local cases
- In September 2023, due to the black rain , many cars broke down in the low-lying area of Lung Cheung Road in Wong Tai Sin, and tow trucks had to wait in line for several hours.
- Lai Chi Kok Road in Sham Shui Po was hit by heavy rain and the water level dropped to half a meter for a short period of time. Several taxis broke down after forcing their way through.
- A private car lost control while driving through flooded water on the Tolo Highway in Fanling and crashed into the roadside guardrail, injuring the driver.
7️⃣ Editor's Exclusive Disaster Prevention Checklist ✅
Before departure:
- Check wipers, washer fluid, and tire tread depth (at least 3mm)
- Watch Observatory warnings and traffic news
- Prepare dashcam footage (to facilitate insurance claims)
While driving:
- Low speed + stable
- Avoid low-lying areas and large reflective water surfaces
- Pay attention to the behavior of the car in front (whether it suddenly slows down or has large waves)
In case of stagnant water:
- Observe the water depth
- Low-speed steady speed
- Keep the throttle slightly open
- If you are not sure, turn around or stop in a safe place to wait for the rain to subside.
8️⃣ Editor’s Summary
"Water can support fish and crops, but it can drown your car on the road."
Heavy rain or flooding is not only about driving skills, but more importantly, it is about safe judgment and careful consideration.
It is better to slow down, change careers or take a different route than to take a gamble and “get away with it” - because if the fire dies out and the fire is damaged, the cost will start from tens of thousands of yuan, and there is also a risk to life.
